Proposed is direct experimental determination of the structure and chemical reactivity of amino acids and related compounds adsorbed at well-defined electrode surfaces in aqueous solutions. Reactivity of these adsorbed layers with species from solution will then be studied. (i) Absolute packing densities of adsorbate (molecules/unit area) will be measured by electrochemistry (EC) in thin-layer cells combined with Auger spectroscopy, to define surface layer composition and adsorbate molecular orientation. (ii) Adsorbate molecular structure and mode of surface bonding will be characterized by infrared reflection absorption spectroscopy (IR) and electron energy-loss spectroscopy (EELS); (iii) Acid-base properties of these well-defined amino acid and related layers will be observed by solution chemistry combined with Auger spectroscopy. (iv) Products, equilibria and rates of reaction of the adsorbed layers with solution of ions, biomolecules, metal complexes and enzyme preparations will be investigated by Auger, EELS, IR and EC. (v) Influence of electrode potential on the above interfacial chemical reactions will then be studied; temperature, pH, substrate, and other variables will also be explored. Those experiments will make use of powerful surface analysis already in place for the purpose in the author's laboratory: three surface-electrochemistry systems equipped for surface characterization by low-energy electron diffraction, Auger, IR, EELS and EC with clean transfer between solution and ultra-high vacuum. Adsorbates to be studied will include amino acids, catechols, alcohols, amines, fatty acids, mercaptans, halide anions, and alkali, alkaline earth and choline cations. Substrates will be well-defined Pt, Ag and stainless steel single-crystal surfaces.